Experimental and numerical investigations of interface properties of Ti6Al4V/CP-Ti/Copper composite plate prepared by explosive welding

Explosive welding technique is widely used in many industries. This technique is useful to weld different kinds of metal alloys that are not easily welded by any other welding methods. Interlayer plays an important role to improve the welding quality and control energy loss during the collision process. In this paper, the Ti6Al4V plate was welded with a copper plate in the presence of a commercially pure titanium interlayer. Microstructure details of welded composite plate were observed through optical and scanning electron microscope. Interlayer-base plate interface morphology showed a wavy structure with solid melted regions inside the vortices. Moreover, the energy dispersive spectroscopy analysis in the interlayer-base interface reveals that there are some identified regions of different kinds of chemical equilibrium phases of Cu–Ti, i.e. CuTi, Cu₂Ti, CuTi₂, Cu₄Ti, etc. To study the mechanical properties of composite plates, mechanical tests were conducted, including the tensile test, bending test, shear test and Vickers hardness test. Numerical simulation of explosive welding process was performed with coupled Smooth Particle Hydrodynamic method, Euler and Arbitrary Lagrangian-Eulerian method. The multi-physics process of explosive welding, including detonation, jetting and interface morphology, was observed with simulation. Moreover, simulated plastic strain, temperature and pressure profiles were analysed to understand the welding conditions. Simulated results show that the interlayer base plate interface was created due to the high plastic deformation and localized melting of the parent plates. At the collision point, both alloys behave like fluids, resulting in the formation of a wavy morphology with vortices, which is in good agreement with the experimental results.     

Damage to aircraft composite structures caused by directed energy system: A literature review

This paper presents a comprehensive review of the research studies on direct energy system effect on aircraft composite structures to develop a good understanding of state-of-the-art research and devel-opment in this area. The review begins with the application of composite materials in the aircraft structures and highlights their particular areas of application and limitations. An overview of directed energy system is given. Some of the commonly used systems in this category are discussed and the working principles of laser energy systems are described. The experimental and numerical studies re-ported regarding the aircraft composite structures subject to the effect of directed energy systems, especially the laser systems are reviewed in detail. In particularly, the general effects of laser systems and the relevant damage mechanisms against the composite structures are reported. The review draws attention to the recent research and findings in this field and is expected to guide engineers/researchers in future theoretical, numerical, and experimental studies.     

2011年度美国参谋长联席会议主席指南

美国参谋长联席会议主席指南是指导联合参谋部工作和联合部队建设的年度文件.2011年度指南提出的优先任务与战略目标有3个:在大中东和中南亚捍卫美国的重要国家利益,改善部队的健康问题,平衡全球战略风险.指南还提出确保联合部队执行新的、废止"不问,不说"的政策,确保整个废止过程有序引导,保持部队的战备.     

锻造海军陆战队特种作战勇士

美国海军陆战队特种作战司令部成立四年以来,能力逐日增强,作战任务多样而繁复,为了应对不断增加的作战需求,司令部对内部结构和规模着手进行调整,单位编组、人员选拔、课程训练等各方面都提出了相应计划,以期用最优状态打赢未来战争.     

俄罗斯19～20世纪战争的结论和启示

在19~20世纪的俄(苏)历史上,发生了包括两次世界大战在内的多场战争,每一场战争,俄国均有失误和错误.本文从分析这些战争的基本结论和教训入手,提出了现代条件下如何进行军事建设的一些思考.